Dealing With Unwanted Plants

August 5, 2024 | C.L. Fornari | Problem Solving

Be they invasive, aggressive, native, or exotic: some plants just have to go.

As we walk through our Cape Cod landscapes in August, it’s common to spot plants that have either appeared this summer or have escaped our attention in the past. Maybe you’re noticing the crabgrass (Digitaria sanguinalis) or spotted spurge (Euphorbia maculata) along the edges of the driveway or between stepping stones. Perhaps you’ve suddenly seen a greenbrier shoot (Smilax rotundifolia) poking out of the tops of your Rhododendrons or Hydrangeas. Or maybe when you look at the perennials in a flower bed you suddenly notice some poison ivy (Toxicodendron radicans) nestled under a daylily. Weeds happen!

Even plants that we like or have purposefully planted can sometimes be such over-achievers that they begin to take over a garden. You may have heard the saying that “A weed is any plant that’s in the wrong place.” and that said, this blog post is about dealing with unwanted plants.

Dig Them or Pull Them

One way to get rid of plants that you don’t want is to pull or dig them out. The advantage to this method is that you get all or most of the roots, so the plant isn’t likely to return. The disadvantage to this method is that it can be time consuming, physical work. Still, when you notice that small poison ivy in the perennial bed, it’s often just as quick to dig it out, and in such cases spraying an herbicide isn’t a good option because surrounding plants will be killed as well.

Smaller poison ivy plants like this one can be dug; use a long-handled shovel, and wear protective clothing. Really tiny ones can be pulled if you put two or more plastic bags over your gloved hands, and grab the plant, turning the bags over the PI once it’s out of the ground. If you are highly allergic to this plant, have someone else deal with it for you. Never put poison ivy plants into a chipper or a fire as the irritating oils can be volatilized and taken into the lungs.

The blackeyed Susans (Rudbeckia) in this garden are starting to take over and need to be edited out. They can be dug or pulled. Note that although these are pretty, reliable perennials, you don’t have to save the ones you’re editing out. Any place that you transplant them too will need editing in the future. Know that it’s okay to toss unwanted plants in the compost pile.

Cut Them Off!

Some unwanted plants are harder to pull or dig because their roots are entwined with others, or so deep and established that it’s impossible to get them all out of the ground. In such cases, cutting them off repeatedly at ground level can, in time, lead to their demise. By cutting the plants off you are denying them photosynthesis, and every time they poke up again they are using energy from the root systems. If you don’t let those plants replace that energy, eventually you’ll starve their roots and they won’t come back. The key is to look for growth once a week and immediately cut it off.

This is Smilex, commonly called greenbrier, cat brier, bull brier or that @(#&*$! vine! It is a native plant, so can’t be considered an invasive, but it certainly is thorny and annoying.

You my see the new shoots of greenbrier poking out of your landscape plants, where it’s impossible to dig them out. Follow that growth back to the ground and cut it off there.

Japanese knotweed is one of the most difficult Cape Cod weeds to get rid of. Read more about knotweed here. If you are using the cut-it-to-the-ground method, you will need to cut this plant weekly without fail, and it may take two or more years for it to die.

Spray With Herbicide

Some plants are best eradicated with an herbicide that kills them, but this method is only good in selected situations. Most herbicides kill whatever they touch, so it isn’t always practical when an unwanted plant grows among others you would like to preserve. There are organic herbicides available, as well as synthetic ones; come into the store to speak with the staff in our Garden Room about the best product for your situation.

There are many choices when it comes to products that will kill unwanted plants. We have a wide range of choices at Hyannis Country Garden. Come in to the store on West Main Street for assistance.

Weeds that are in between pavers or in gravel are more easily dealt with an herbicide since there aren’t other plants nearby that you want to save.

Correct The Growing Conditions That Weeds Favor

Many weeds thrive in particular conditions, and if you change that environment the weeds are less likely to grow. Sheep sorrel (Rumex acetosella), for example favors acidic soils, and spurge, crabgrass, and purslane like dry, hot areas. Plantain and speedwell show up when soil is compact. If you have weeds in your lawn or gardens, come talk with our green team in the store to learn how you can change the growing conditions there so that the turf out-competes the undesirables.

Rumex acetosella, commonly called sheep sorrel, red sorrel or just sorrel, has longer leaves than the other winter weeds and like the dandelion, is a perennial. One means of fighting this weed is to lime the area as long as the other plants you’re growing there like a neutral pH of soil. (Don’t lime around Rhododendrons or holly, for example.) Sorrel grows very well in acidic soil but not so well when the pH is raised.

Grow More of What You Desire, and Keep That Thriving!

Places where your soil is bare are likely to contain weeds. Mulch can help prevent weed seeds from germinating, but where other plants are thick and healthy you already have the ground shaded. Geranium macrorrhizum, Epimedium, lady’s mantle (Alchemilla mollis) and Hosta, for example, make great weed-smothering ground covers in part to full shade. ‘Zagreb’ Coreopsis, wooly thyme (Thymus pseudolanuginosus), and creeping phlox (Phlox subulata) do the same in full sun. And a lawn where the grass or grass and clover are vigorous are much less likely to contain other plants.

Epimedium is a problem-solving plant. It grows in shade and is drought tolerant. It’s also weed smothering because it grows very thickly. This lovely plant is the perfect groundcover for shade and combines beautifully with hosta.

For more about the vines and other invasives that commonly appear in Cape Cod landscapes, read this blog post from 2020.

Posted in Problem Solving